Engineered structures that can alter the speed of light could benefit optical communication systems
A method for designing materials capable of slowing the propagation of light over a broad range of wavelengths has been developed by researchers at the A*STAR Institute of High Performance Computing .
The speed of light in a vacuum is always constant — a fundamental concept made famous by Albert Einstein. But light propagates more slowly when it enters a different medium, such as glass.
The degree to which the speed is reduced is given by a material’s dielectric constant — a higher dielectric constant indicates slower propagation. Rather than rely on a limited source of natural substances, scientists have started to design optical materials with a broader range of beneficial properties including ‘slow’ light.
One approach is to combine two materials with different dielectric constants into a periodic structure. This can result in properties that dramatically differ from those of the constituent materials, particular when the length scale of the periodicity is similar to the wavelength of light.
“These so-called photonic crystals, when appropriately designed and in ideal conditions, can almost stop the propagation of light altogether,” says A*STAR scientist Gandhi Alagappan.
The requirement that the periodicity of the structure be similar to the wavelength of interest, however, is a limitation for practical applications. It means that most of these materials only work with light of a single color. Alagappan and his co-worker Jason Ching Png have now developed a scheme for designing photonic crystals that operate over a broader range of wavelengths.
Alagappan and Png considered a structure in which two different materials are layered on top of each other. To obtain two different periodicities, however, a third material with a dielectric constant midway between the two other materials would typically be needed.
This makes physically creating the structure difficult. The researchers instead focused on developing a mathematical technique to combine two materials in such a way that the dielectric profile in the stacking direction is almost the same as in the more complicated three-material structure (see image).
Alagappan and Png simulated the optical properties of their combined photonic crystal. They identified a broad range of wavelengths known as the strong coupling region that has a high density of slow modes.
“We have invented a linear optical multi-scale architecture that facilitates the creation of broadband slow light,” says Alagappan. “The proposed structure could potentially revolutionize current optical buffering technologies.”
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing. More information about the group’s research can be found at the Photonics and Plasmonics Group webpage.
 Alagappan, G. & Png, C. E. Broadband slow light in one-dimensional logically combined photonic crystals. Nanoscale 7, 1333–1338 (2015).
A*STAR Research article
A*STAR Research | ResearchSEA
Putting food-safety detection in the hands of consumers
15.11.2018 | Massachusetts Institute of Technology
Next stop Morocco: EU partners test innovative space robotics technologies in the Sahara desert
09.11.2018 | Deutsches Forschungszentrum für Künstliche Intelligenz GmbH, DFKI
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences